UVA11275 3D Triangles（三维几何）

https://www.luogu.com.cn/problem/UVA11275

三维入门入门，贴个板子。

#define IO std::ios::sync_with_stdio(0)
#include <bits/stdc++.h>
using namespace  std;
const double eps=1e-6;

int dcmp(double x){
    if(fabs(x)<eps)return 0;
    return x<0?-1:1;
}
struct Point3{
    double x,y,z;
    Point3(double x=0,double y=0,double z=0):x(x),y(y),z(z){}
};

typedef Point3 Vector3;

Vector3 operator +(Vector3 A,Vector3 B){
    return Vector3(A.x+B.x,A.y+B.y,A.z+B.z);
}
Vector3 operator -(Point3 A,Point3 B){
    return Vector3(A.x-B.x,A.y-B.y,A.z-B.z);
}
Vector3 operator *(Vector3 A,double p){
    return Vector3(A.x*p,A.y*p,A.z*p);
}
Vector3 operator /(Vector3 A,double p){
    return Vector3(A.x/p,A.y/p,A.z/p);
}
bool operator ==(const Point3 &a,const Point3 &b){
    return dcmp(a.x-b.x)==0&&dcmp(a.y-b.y)==0&&dcmp(a.z-b.z)==0;
}
double Dot(Vector3 A,Vector3 B){
    return A.x*B.x+A.y*B.y+A.z*B.z;
}
double Length(Vector3 A){
    return sqrt(Dot(A,A));
}
double Angle(Vector3 A,Vector3 B){
    return acos(Dot(A,B)/Length(A)/Length(B));
}
double popldis(Point3 p,Point3 p0,Vector3 n){
    return fabs(Dot(p-p0,n));
}
Point3 pty(Point3 p,Point3 p0,Vector3 n){
    return p-n*Dot(p-p0,n);
}
Point3 lineplane(Point3 p1,Point3 p2,Point3 p0,Vector3 n){
    Vector3 v=p2-p1;
    double t=(Dot(n,p0-p1)/Dot(n,p2-p1));
    return p1+v*t;
}
Vector3 Cross(Vector3 A,Vector3 B){
    return Vector3(A.y*B.z-A.z*B.y,A.z*B.x-A.x*B.z,A.x*B.y-A.y*B.x);
}
double Area2(Point3 A,Point3 B,Point3 C){
    return Length(Cross(B-A,C-A));
}
bool PointTri(Point3 p,Point3 p0, Point3 p1,Point3 p2){
    double a1=Area2(p,p0,p1);
    double a2=Area2(p,p1,p2);
    double a3=Area2(p,p2,p0);
    return dcmp(a1+a2+a3-Area2(p0,p1,p2))==0;
}
bool segtri(Point3 p0,Point3 p1,Point3 p2,Point3 A,Point3 B,Point3 &P){
    Vector3 n=Cross(p1-p0,p2-p0);
    if(dcmp(Dot(n,B-A))==0)return false;
    else{
        double t=Dot(n,p0-A)/Dot(n,B-A);
        if(dcmp(t)<0||dcmp(t-1)>0)return false;
        P=A+(B-A)*t;
        return PointTri(P,p0,p1,p2);
    }
}
double ptoline(Point3 P,Point3 A,Point3 B){
    Vector3 v1=B-A,v2=P-A;
    return Length(Cross(v1,v2))/Length(v1);
}
double ptoseg(Point3 P,Point3 A,Point3 B){
    if(A==B)return Length(P-A);
    Vector3 v1=B-A,v2=P-A,v3=P-B;
    if(dcmp(Dot(v1,v2))<0)return Length(v2);
    else if(dcmp(Dot(v1,v3))>0)return Length(v3);
    else return Length(Cross(v1,v2))/Length(v1);
}
double Volume6(Point3 A,Point3 B,Point3 C,Point3 D){
    return Dot(D-A,Cross(B-A,C-A));
}
void readp(Point3 &p){
    scanf("%lf%lf%lf",&p.x,&p.y,&p.z);
}

Point3 p[10];
int T;
int main(){
    scanf("%d",&T);
    while(T--){
        for(int i=0;i<6;i++){
            readp(p[i]);
        }
        int f=0;
        if(segtri(p[0],p[1],p[2],p[3],p[4],p[6]))f=1;
        if(segtri(p[0],p[1],p[2],p[3],p[5],p[6]))f=1;
        if(segtri(p[0],p[1],p[2],p[4],p[5],p[6]))f=1;
        if(segtri(p[3],p[4],p[5],p[0],p[1],p[6]))f=1;
        if(segtri(p[3],p[4],p[5],p[0],p[2],p[6]))f=1;
        if(segtri(p[3],p[4],p[5],p[1],p[2],p[6]))f=1;
        printf("%d
",f);
    }
}